class Animal {
  constructor(){
    this.name = 'Animal';
  }
  age;
  personName;
  set name(personName) {
    this.personName = personName;
  }
  set age(age) {
    this.age = age;
  }

  get age() {
    return this.age;
  }
}

export class Person extends Animal {
  constructor(personName){
    super(personName, personName);
    this.name = 'person';
  }
  age;
  personName;
  setName(personName) {
    this.personName = personName;
  }
  setAge(age) {
    this.age = age;
  }
  sing() {
    return '一个会唱歌的人';
  }
}


